You could hang out at the pool for a couple of hours, then have a nice dinner.
You could take the either boat over to FW to check out the farm animals, let the kids have a pony ride (closes at 5, $3, closed toe shoe required). Have dinner at Trails End. Or do the Hoop De Doo or Mickeys BBQ. Go to the evening campfire and/or movie. (you'll get a schedule when you check in.)
You could take the blue launch boat over to CR, explore, then hop the monorail to the Poly & GF and explore each resort.
WL is so beautiful, I don't think you'll have trouble filling your afternoon! During our stay, we were generally done with the parks by 2 or 3 and just swam, had dinner, and relaxed.
Also, you can rent water mice and/or bikes. There is a trail to FW.